Elevation of granular solids



'March 26, 1963 w. L. MQCLURE 3,083,054

ELEVATION 0F GRANULAR SOLIDS Filed Oct. 17, 1960 2 Sheets-Sheet 1 I INVHVTQRK WILLIAM L. MC OLJJRE UZ/Lw s w TTORNE Y March 26, 1963 w. 1.. MCCLURE 3,033,064

ELEVATION OF GRANULAR souos Filed Oct. 17, 1960 2 Sheets-Sheet 2 INVENTOR. WILLIAM L. MC OLURE J W-+0. Wal

ATTORNEY 3,083,064 ELEVATION Oi GRANULAR SULIDS William L. McClure, Toledo, Ohio, assignor to Sun Oil Company, Philadelphia, la., a corporation of New Jersey Filed Oct. 17, 1969, Ser. No. 63,177 Claims. (Cl. 30259) This invention relates to the pneumatic elevation of granular solids and more particularly to improved apparatus for the disengaging of granular solids from lifting gas following the passage of a suspension of the solids in lifting gas through a plurality of lift conduits.

In various commercial processes for pneumatic elevation of granular solids, a plurality of lift conduits are employed communicating with a common disengaging vessel. For a given rate of transfer of granular solids, it is often desirable to divide the total flow among a plurality of small lift conduits rather than to pass the entire amount through a single large conduit. It is easier to obtain' stabilized flow of solids through a smaller lift conduit, e.g. 8" in diameter, than through a large conduit, e.g. 20" in diameter. With the latter there is a tendency for uneven velocity distribution over the cross section of the conduit, and this frequently results in undesirable fall-back of solids in the portions of the cross section wherein the velocity is relatively low.

In installations where a plurality of lift conduits com- Inunicate with a single disengaging vessel, a problem is presented in that there is a tendency for solids which are discharged from one conduit to fall downwardly toward the upper end of another conduit. This results in undesirable striking of the falling particles against the particles arising from the latter conduit. In order to overcome this problem, it has been proposed in the prior art to divide the disengager cross section into a plurality of compartments, employing vertical partitions to separate the compartments, and providing a separate compartment for each of the lift conduits. Such construction is disclosed, for example, in Patent No. 2,674,498 of Clarence H. Thayer, April 6, 1954. In practice, this construction has also presented problems, since it has been found that a portion of the solids in each compartment falls directly downwardly toward the upper end of the lift conduit, rather than passing laterally toward the wall of the disengager vessel as desired. Also some of the solids pass laterally toward the axis of the disengager vessel rather than toward the wall of the vessel as desired. These flow patterns result in undesirable attrition of the solids as a result of the striking of the falling particles against rising particles, and also result in undesirable erosion of metal surfaces in the disengager vessel.

The present invention provides apparatus for disengaging granular solids from lifting gas, whereby the undesirable features of prior art apparatus are eliminated, and a highly satisfactory system is provided wherein a plurality of lift conduits communicate with av single disengaging vessel.

The invention will be further. described with reference to the attached drawings, wherein FIGURE 1 is a schematic flow sheet of a granular solid circulating system to which the invention is applicable, FIGURES 2 and 3 are sectional plan and sectional elevation views respectively of a disengaging vessel according to one embodiment of the invention, and FIGURES 4 and 5 are sectional plan and partial sectional elevation views respectivelyof another embodiment of the invention.

In FIGURE 1, a reaction vessel 2, a regeneration vessel 4, a pneumatic lift engaging vessel 6, a lift conduit system 12 and a disengaging vessel are shown. In operation, granular solid catalyst is gravitated through reaction vessel 2 as a compact bed and contacts therein fluid 3,083,064 Patented Mar. 26,. 1963 reactants under conditions for conversion of the reactants" catalyzed by the granular solids. The-reaotionproduots" are withdrawn through means not shown. Thegra'nular" solid catalyst, now containing carbonaceous depositsas a result of reactions occurring in vessel 2, are" passed by gravity into regeneration vessel 4, wherein the catalyst" is contacted with oxygen introduced through means not shown, under combustion conditions whereby the deposits are burned in order to regenerate the'catalyst." The re generated catalyst is passed by gravity into engager 6',

lift conduit system 12 is composed of a plurality of lift conduits not individually shown in FIGURE 1.

In FIGURES 2 and 3, the disengager vessel 10 is shown in more detail. A transverse partition 14" is pro vided'in'a lower portion of the vessel, and the lift conduits 12 extend-upwardly through apertures in the partition; The conduits 12 are not secured with-in theaperture. Be-' cause of thermal expansion of the lift conduits upon the passage of hot solids therethrough, it is necessary that the walls of the lift conduits be capableof moving verftically in relation to the partition'14.

A hollow conical baflie 16 has its lower end secured within an aperture in the cen-ter'of the partition'1 4. This baffle intersectswithin vessel 10 the imaginary upward projections of each of the lift conduits 12. Secured to the top of baflie .16 is a funnel-1'8." Secured to the inner wall of vessel 10 is a transverse annular plate 22 having therein a plurality of apertures 24, the latter being spaced around'the cross section of the vessel i n" an approximately annular pattern. A continuous annular aperture can' if desired be employed in place of the plural apertures 24'. Secured to .the outer edge of plate 22 is a vertical annular baffle 26. i W

In operation, solids suspended in lifting gas are dis charged upwardly from the upper ends of the lift con duits 12-and rise through the portion of the vessel 10 above the upper ends of the lift conduits. The upwardly expanding baffle 16 causes the granular solids to'be" gradually moved laterally toward the wall of disengager 10; thereby effectively preventing the solids from falling di rectly downwardly toward the upper end of the lift conduit. The solids pass-upwardly above the plate 22, until they reach the" upper limit of their travel, and then fall downwardly onto the plate 22. The lifting gas rises above the funnel 18 and passes-into the outlet 2th A small proportion of the total solids in the system is carried by the gas above the funnel 18' and drops out of the gas before the latter enters the outlet 20. These solids pass downwardly through the funnel 18and the interior" of the bafile 16 and are-introduced into the portion of thevessel 10 beneath the partition 14.

Granular solids collect on the plate22' in the piles 28 and subsequently pass downwardly throughtheap'ertures 24 onto the piles 32 on the partition 14; From" the latter piles, the solids pass through the apertures 30 in the par tition 14-and are collected in a bed 34, fromwhich solids are passed by! gravity through the outlet'36? The apertures 24 in the plate-:22 arespaced inwardly from the wall of vessel 10 in order that the solids falling beneath plate 22 do not come in contact with the wall of vessel 10. Erosion of the wall is thereby avoided. The piles 28 on the plates 22 are beneficial in that solids falling toward the plate 22 come in contact with the solids in the piles 28, rather than with the wall of vessel 10.

this avoids attrition of the solids and erosion of the wall which would otherwise take place.

If desired the lower portion of the vessel 10 can be used as a surge hopper by maintaining the upper surface of the bed 34 below the apertures 30 so that solids fall beneath the apertures'dll'rather than pass directly therefrom into the bed 34. Other known means for providing a surge hopper in the lower part of a disengagervessel can alsobeemployed. t Y

FIGURES 4. and'S illustrate a generally similar embodiment to' that shownin FIGURES 2 and 3. One principal diiference resides in the use of a baffle 16 which has the shape of an inverted pyramid, the cross section of the bafile being square. This construction is advantageous in that it is particularly suitable for preventing the solids which rise from one lift conduit from falling toward the upper end of another lift conduit.

In the embodiment of FIGURES 4 and 5, the bafiie 16 is in two sections, the walls of which are at different angles with the vertical. The upper section 42 is at a greater angle with the vertical than the wall of the lower section 44. As the solids rise from the conduits 12 through'the region adjacent the lower portions 44 of the bathe 16, the velocity of the solids is relatively high, whereas it is relatively low during passage of the solids through the region adjacent the upper portion 42 of the baffle Whenthevelocity is relatively high, a relatively smallangle of the baffle with the vertical is effective to provide the desired lateral movement awayiro'rh' the bafile, and avoids excessive erosion of the bafiie wall. When the velocity is relatively low, on the other hand, a

. greater angle with the vertical is desirable in order to provide the desired lateral movement, and at the lower velocities does not result in excessive erosion of the bafiie wall.

A circular plate 46 is suspended by rods 48 from the top of the vessel 10, and the lifting gas passes upwardly around the plate 46 in order to enter theoutlet 20. The bathe 16 may the hollow, asin the embodiment of FIG- URES 2 and 3, in order to convey any solids which fall thereinto to the lower portion of the vessel 10. It is also within the scope of the invention to employ a bafiie which is solid, or which is hollow bllll; closed at the top.

In place of the baflle 16 having two sections 42 and 44 whose walls are at different angles with the vertical, a battle can be employed, the angle (with the vertical) of the wall of which gradually upwardly increases.

Preferably the angle with the vertical'of the wall of the baffle 16 is in the range from 1 to 10. In the embodiment of FIGURE 5, the angle of the lower portion is preferably inthe range-from 1 to 5, and of the upper portion in the range from 5 to 1 In a typical installation, eight lift conduits are employed, each 8 inches in diameter. The upper ends of the lifit conduits are, during operation, about three feet above the partition-l4, and are each about one inch from the baflle 1 6,which is an inverted conical frustum whose wall is at an angle of 3 with the vertical for a height up to five feet above the upper ends of the conduits 12,- and at an angle of 7 with the vertical for the portion from five feet to ten feet above the upper ends of the conduits, the total height of the bathe 16 being 13 feet.

In operation, granular solid synthetic silica-alumina cracking catalyst having particle size primarily'in the 3 to 8 mesh range is elevated through the conduit at a rate of 35 pounds per'hour per conduit. The height of rise of the catalyst above the upper ends of the lift conduits is somewhat less than 10 feet. A uniform flow pattern of solids isobtained in the disengager vessel, the catalyst flowing upwardly and laterally in a substantially linear pattern without eddies, and being collected on the plate 22. Fall-back of catalyst onto the upper ends of the lift conduits, or onto the catalyst rising therefrom, is substantially eliminated. Catalyst attrition and erosion of metal parts are thereby substantially reduced, as compared with operation in the absence of the baffle 16. Higher velocities of gas and solids in the lift conduits,

, and higher throughputs of solids, can be employed and obtained, since the avoidance of solids fall-back to the upper ends of the lift conduits makes it possible to use higher exit velocities of the solids from the lift conduits without excessive attrition.

The height of the bafiie 16 is preferably such that the top thereof is above the top of the fountain of solids in the disengager. This in iturn depends on the velocity of the solids" on discharge from the lift conduits and other factors. The baffle 16 is sufliciently high that it inte'rsects within the disengager, the imaginary upward projection of each of the lift conduits, in order to obtain optimum effect in moving the solids laterally toward the disengager wall. Preferably, such intersection takes place at a distance above the upper end of the lift conduit which is not more than three times the diameter of the lift conduit at its upper end. The baflie 16 preferably has gradually upwardly increasing cross section through at least half its height, and more preferably through its entire height.

The invention claimed is:

1. Apparatus for elevating granular solids which comprises a plurality of upwardly extending lift conduits; means for introducing granular solids and lifting gas into each lift conduit; a receiving vessel having an upwardly extending baffle centrally located therein, the horizontal cross section of which baflie gradually upwardly increases; the upper open ends of said lift conduits being positioned Within said vessel and being spaced around said baffle at a level below the upper end of said baffle; and means for separately removing lifting gas from an upper portion of said vessel and granular solids from a lower portion of said vessel.

2. Apparatus according to claim 1 and additionally comprising a transverse annular plate secured to the inner wall of said vessel and extending inwardly therefrom at a level between the upper ends of said lift conduits and the upper end of said baflle, said plate having an aperture therein spaced inwardly from said wall; and a vertical annular baflie extending upwardly from the inner edge of said plate.

3. Apparatus according'to claim 1 wherein said baflie is hollow and communicates at its lower end with a receiving zone in a lower portion of said vessel.

4; Apparatus according to claim 1 whereinsaid bafiie intersects within said vessel the imaginary upward projections of said lift conduits.

5. Apparatus according to claim 1 wherein said baffle has an upper portion and a lower portion, and the angle of the sidewall of the lower portion with the vertical is less than the angle of the sidewall of the upper portion with the vertical.

References Cited in the file of this patent UNITED STATES PATENTS 2,674,498 Thayer Apr. 6, 1954 2,753,221 Thayer July 3, 1956 2,767,031 Huffman Oct. 16, 1956 2,809,871 Ardern Oct. 15, 1957 2,862,7'7 1 Lebeis Dec. 2, 1958 2,873,144 Bergstrom Feb. 10, 1959 2,873,147 Payne Feb. 10, 1959 

1. APPARATUS FOR ELEVATING GRANULAR SOLIDS WHICH COMPRISES A PLURALITY OF UPWARDLY EXTENDING LIFT CONDUITS; MEANS FOR INTRODUCING GRANULAR SOLIDS AND LIFTING GAS INTO EACH LIFT CONDUIT; A RECEIVING VESSEL HAVING AN UPWARDLY EXTENDING BAFFLE CENTRALLY LOCATED THEREIN, THE HORIZONTAL CROSS SECTION OF WHICH BAFFLE GRADUALLY UPWARDLY INCREASES; THE UPPER OPEN ENDS OF SAID LIFT CONDUITS BEING POSITIONED WITHIN SAID VESSEL AND BEING SPACED AROUND SAID BAFFLE AT A LEVEL BELOW THE UPPER END OF SAID BAFFLE; AND MEANS FOR SEPARATELY REMOVING LIFTING GAS FROM AN UPPER PORTION OF SAID VESSEL AND GRANULAR SOLIDS FROM A LOWER PORTION OF SAID VESSEL. 